MPs from four influential committees are coming together to launch a joint inquiry into the scale and impact of the UK’s air pollution crisis.

In an unusual development, the environmental audit committee, environment, food and rural affairs committee, health committee and transport committee will hold four sessions to consider mounting scientific evidence on the health and environmental effects of toxic air.

Dr Sarah Wollaston, the health committee chair, said poor air quality was “affecting the health of millions of people across the UK”.

“Our joint inquiry will include an examination of the scale of the harm caused and the action necessary to tackle it,” she added.

The government says toxic air causes up to 50,000 early deaths – 9,000 of them in the capital – and costs the country £27.5bn each year.

The government’s own statistics show 38 out of 43 UK “air quality zones” breach legal limits for air pollution and last year the high court ruled ministers must cut the illegal levels of NO2 in dozens of towns and cities because their current policies to improve air quality were so poor they were unlawful.

The government has to announce its new plans before 24 April and the inquiry will examine whether these proposals go far enough to cut pollution “not only to meet legal limits but also to deliver maximum health and environmental benefits”.

Mary Creagh, chair of the environmental audit committee, said: “The UK courts have twice found that the government has failed to deal with our air pollution problem properly. Now ministers will face unprecedented scrutiny in parliament to ensure they finally step up to the mark to ensure adults, and children in particular, do not have their health damaged by filthy air.”